Pressure relief device



Dec. 21, 1943. J. J. VIENNEAU PRESSURE RELIEF DVICE Filed Aug. 11, 1942 mil Inventer: Jacob J.Viemne au,

H is Att or ny.

Patented Dec. 21, 1943 PRESSURE- RELIEF DEVKCE Jacob J. Vienneau, Pittsfield, Mass., assigner to General Electric Company, a corporation of N ew York 4 Claims.

My invention relates to a pressure relief device for an enclosing casing of electrical apparatus, and to a device for rupturing a fiangible diaphragm upon the occurrence of an abnormal operating condition, such as excess pressure.

Eiectrical apparatus which are totaliy enclosed in a casing are usually susceptible t relatively high pressures being developed in the casing under certain conditions, such as When a fault occurs in the apparatus inside the casing. It is eustomary, thereiore, to provide pressure relief devices inciuding frangible diaphragms which will rupture and relieve the high pressure whenever such an abnorinal pressure condition obtains within the casing. It is sometimes difficult to provide a frangible cliaphragm which Will Withstand normal pressures indefinitely and which Will consistently release pressures which would damage the tank and electrical apparatus. In order to overcome this clifiiculty spring operated plungers have been provided which are released for cperation when an abnormal pressure obtains within the casing, the plunger being forced against th diaphragm to rupture it. Such a structure described in Patent 1,670,697, Treanor, which patent is assigned to the same assignee as this present invention.

It is thereiore an object of my invention to provide an improved device for rupturing a frangioie diaphragm upon the occurrence of an abnormal operating condition.

Another object of my invention is to provide an improved device for rupturing a pressure re- 1ief diaphragm which is placed in the casing of an electrical apparatus.

Further objects and advantages of my invention Will become apparent from the following descripton referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out With particularity in the claims annexecl to and forming a part of th s specification.

In the drawing, Fig. 1 is a side elevation in partial section of a transformer casing which is provided with an embodiment of my invention; Fig. 2 is a side view of the diaphragm rupturing device of Fig. 1; Fig, 3 is a top view of the device of Fig. 2; Fig. 4 is a side view of the diaphragm rupturing device taken along the limes i of Fig. 3; Fig. 5 is a perspective view of a portion of the operating mechanism of the device in Figs. 1 to 4:; Fig. 6 is a sectional side clevation of the operating mechanism of Fig. 5; and Fig. 7 is a sectional side elevation of a portion of the device after operation in response to an aonormal operating condition, such as en abnormai pressure.

Referring to Fig. 1 of the drawing, I have illustratecl a casing ii.a for any apparatus, such as a transformer having a core il and Windings i2. Such apparatus usually has an insulating fiuid, such as cil, partiy filling the casing and With a gas above the oil. At the top of the casing there is provided a suitabie frangible diaphragm i3 Which is adapted to be ruptured by my improved devise upon a predetermined abnormal condition, such as pressure obtaining within the casing til. The diaphragm i3 may be supported in any suitable manner such as being attached to a collar i WhCI is in turn attached to the top of the casing iEi. Inside the transformer casing and suitably positioned with respect to the diaphragrn 3 is placed my improved device indicated generally by the numeral 35. This device has a plunger i6, as will be seen more clearly in 2, with a sharp point i! in the end tirereof. The plonger i6 is normally held With its point li away from the diaphragm i3. However, upon the attainment of a predetermined abnormai pressure the plunger i5 is released so that the sharp point il will be forced against the diaphragm i3 -with suificient pressure to rupture it and relieve the excess pressure within the tank m. Since the diaphragm js ruptured by a sharp point et the desired pressure, the diaphragm may be made of any strong material, such as ternpered glass.

In order to mount the plunger E5 in suitable relationship With respect to the diaphragm et, a base plate !8 is provided having openings i9 (see Fig.3) for bolting the base plate to the inside portion of a collar member 2@ which is suitably attached to the inside of the transformer casing !l. The base plate is also provided with a bearing portion 2i having an opening 22 within which the plunger ii is supported and longitudinally movable.

In order to hold the plunger 55 in a first position or in 2. position With the point il away from the diaphragm 53 as is illustrated in Figs. 1 to 6, I provide an arrangement including a shait 23 which is rotatably mounted at its ends 2 i and 25 in suitable holes in the base portion 21 In order to hold the plunger 53 in the position iliustrated in Figs. 1 t0 5, the plunger and shaft 23 are eacn provided with cooperating stops or suri aces. This may ce aceomplished in any suLabie manner,

such as by providing a. cutout portion 28 on the plunger Hi and a cutout portion 27 on the shaft 23, the plunger and shaft being so situated With respectto each other that relatively small surfaces or edges on the cutout portions 26 and 21 cooperate to hold the plunger 16 in its first position, as is illustrated clearly in F1gs, 2 and 6. It W111 also be seen that shaft 23 extends transverse- 15 with respect to the axis of the plunger 16 so that a re1atively s11ght rotatable movement of the shaft 23 W111 move the' surface 21 out 01 contact With the edge 26 so that the plunger 16 W111 no longer be held in the position as illustrated in Figs. 1 to 6.

In order to bias the plunger 16 to a second or cuttng position there is provided a b3asing arrangement including a spring 39 which has one end supported by an end portion 31 01 the base member 21, the other end being supported by a stud 32 near the point 11. It W111 be seen that when the plunger is in theposition illustrated 7 between the shafts being made by an arm 33 which s rigidly attached at one end to the shaft 23. The opposite end 35 of the arm is he1d by an edge 36 of the shaft 33. The shaft 33 is mounted for limited rotatable movement in a portion 37 of the base member 21. It W111 be noted particu1arly that the shaft 33 has a relatively sinall surface which contacts the end 35 of the arm 3 1. This is accompfished by cutting a portion of the end of the shaft 33 so as to provide the half round portion 36. As W111 be seen clearly in Figs. 2 and 6, a very small rotation of the shaft 33 W111 move the ha1f round portion 36 so that the end 35 of the arm 36 W111 be 1eft unsupported. Ihis W111 in turn allow the shaft 23 to move which W111 in turn allow the spring 39 to force the plunger 16 to its second position.

In order to accomplgh the s1ight rotation of the shaft 33 50 as to trigger the device, the opposite end 40 of the shaft 33 is attached to a longitudinally movable rod 11 which moves when the predetermned abnormal condition of pressure obtains, This may be accompiished in any suitable manner such as by connecting the rod 41 to a Sylphcn be11ows 42, the beilows be1ng attached to the base member 21 at 13. A connecti0n is made between the rod 11 and the shaft 33 through connector member 1 2. The connector member M is biased by a spring 55 so as to bias the shaft 33 for rotatable movement in a c0untercleckwise direction when looking at Fig. 2.

So that the bellows member 2 may be substant1ally unafieeted by changes in temperature Within the transformer casing 511, the bellows having a suitab1e opemng 6- (see Fig. 3) is heated t0 expel the air. The be11ows in this condition is a1so compressed so as to further accompfish the expelling of the air, and while in this condition the ho1e 46 is 'c1osed in 'any suitable manner, such as by placing a lump of solder 41 over the hole 13. In order to prevent collapse of the bellows, since it is partially evacuated, a suitable spring 48 (see Fig. 1) is p1aced inside, the spring being .suitabiy calibrated so that it will allow the bellows t0 contract sufi- 'cientl uPon a predetermined abnormal condition of pressure obtaining within the tank enclosure l0.

Operation of my device is as follows. When a pressure of a predetermmed amount obtains Within the tank 10, the Sylphon bellows 32 W111 co11apse, thus causing movement of the rod 41 toward the bellows. Through the link member 44 this W111 cause the shaft 33 to rotate in a clockwise direction (see Fig. 2) until the end 35 of the arm 34 is no longer supported by the end 36 of the shaft 33. Since the plunger IS 15 iased to move toward the diaphragm 13, the pressure of the spring W111 now force the stop surface 27 by 1otating the shaft 23 until the surface 27 is out of contact with the surface 26. The p1unger 16 W111 then be free to move unti1 a stop or 'nut 511 and wasber 51 on an end of the p1unger contact the space member 21, this position being illustrated in Fig. 7. The shaft 23 W111 rotate until the end 35 of the arm 34 contacts a stop member 52.

As W111 be seen in Fig. 6, the fiat surface 21 of the shaft 33 is placed at a slight angle with respect to the fiat surface 26 of the plunger 16 so that the point 01 contact 53 may be as close to the center line 54 of the shaft as is prac tica1. With this construction 1t W111 oniy take a re1atively sma1 force between the end 35 of the arm 34 and the edge 36 of the shafc 33 so as to hold the arm 34 in the position illustrated in Fig. 6.

The devce may be easily reset by removing the damaged diaphragm 13 and pushing the plunger 16 to its first position and resettng the stop surfaces. In order to adjust the predetermined abnormal pressure which W111 operate the device I provide an adjusting mechanism inc1uding a nut 55 on the end ct the rod 41. By backing off the look nut 56 and disp1acing the link 4 With respect to the rod 41 it W111 be seen that the p1edetcrmined pressure at which the device operates W111 be raised.

Although I have shown and described a particu1ar embodiment of my invention, I do not desire to be limited to the particu1ar embodi ment described, and I intend in the appended claimg to cover all modifications which do not cepa1t from the spirit and scope of my invenion.

What I daim as new and desire to secure by Letters Patent of the United States 15:

1. In a device for rupturing a frangble diaphragm, a plunger biased for movement from a first to a second position, means for holding said plunger in said first position including a rotatable shaft extendmg transversely of said plunger, said p1unger and shaft having stops With relatively sma1l engaging surfaces so that a s1ight movement of said shaft W111 re1ease said plunger, an arm connected to said shaft, means for holding said arm against movement includ- 'ing a second shaft,amd means for moving said second shaft upon the occurrence of a predetermined abnormal pressure so as to allow movement of said first shaft and disengagement of said stops.

' 2. Ina device for rupturing a frangble diaphragm, :a plunger based for movement from a first to a second position, means for holding said plunger in said first position including a rotatable shaft exteriding transversely of said plunger, said plunger and said shaft having cutout portions presentir1g cOoperating surfaces, an arm connected to said shaft, means for holding said arm againstmovement including a secrotatable shaft extending transversely of said p1unger, said plunger and said shaft having cutout portions, an arm connected to said shaft, means for holding said first shaft and arm against movement including a second rotatabie shaft having an edge engaging an edge of said arm, and means for moving said second shaft upon the occurrence of a predetermined abnormal pressure so as to disengage said edges and a1low movement of said plunger.

4. In a device for rupturing a frangible diaphragm, a, plunger biased for movement from a, first t0 a second position, means for holding said plunger in said first position including a. rotatabie shaft extending transversely of said plunger, said piunger and said shaft having cutout portions, said p1unger contacting a. radia! surface of said shaft relatively close to the longitudinal axis of said shat, an arm connected to said shat, means for holding said first shaft and a1m against movement including a second rotatable shaft having an edge engaging au edge of said arm, a pressure responsive means, and means for connecting said pressure responsive means to said second shaft including en adjustabie means for regulating the pressure at which said second shaft Will move out ci engagement with said arm.

JACGB J. VIENNEA. 

